JP6070635B2 - Semiconductor device - Google Patents

Description

  The present invention relates to a semiconductor device.

  2. Description of the Related Art A semiconductor device that monitors the temperature of an IGBT using the temperature dependence of a forward voltage of a diode is known (see, for example, Patent Document 1). In this semiconductor device, the temperature of the IGBT to which the freewheeling diode is connected in antiparallel is monitored by detecting the forward voltage of the temperature detecting diode provided in the same chip as the IGBT chip.

JP 2013-183595 A

  However, a free-wheeling diode connected in antiparallel to a switching element such as an IGBT is one of heat generation sources. For this reason, in the conventional technique for detecting the forward voltage of a temperature detecting diode separate from the freewheeling diode, the heat conduction time from the freewheeling diode to the temperature detecting diode is delayed, so the temperature detection accuracy is low.

  In addition, since the temperature dependence of the forward voltage of the diode decreases as the current density of the diode increases, the current density of the freewheeling diode is detected even if the forward voltage of the freewheeling diode connected in reverse parallel to the switching element is detected. Depending on the size, the temperature detection accuracy may decrease.

  Therefore, an object is to provide a semiconductor device capable of detecting temperature with high accuracy.

One idea is that
A switching element;
A first freewheeling diode connected in antiparallel to the switching element;
A current path connected in parallel to the first freewheeling diode;
A second freewheeling diode inserted in series with the current path;
Temperature detecting means for detecting a temperature based on a difference voltage between a forward voltage of the first freewheeling diode and a forward voltage of the second freewheeling diode;
A semiconductor device is provided in which the current density of the first free-wheeling diode and the current density of the second free-wheeling diode are different from each other.

  According to one aspect, since the first free-wheeling diode and the second free-wheeling diode are heat sources, the temperature can be detected with high accuracy by using the forward voltage of the heat source itself for temperature detection. Further, according to one aspect, when the current density of the first freewheeling diode and the current density of the second freewheeling diode are different from each other, the temperature dependence of the above-mentioned differential voltage is the forward voltage of the single freewheeling diode. The temperature can be detected with high accuracy because it is less likely to decrease than temperature dependency.

Configuration diagram showing an example of a semiconductor device The figure which shows an example of the temperature dependence of the forward voltage of a diode The figure which shows an example of the temperature dependence of the forward voltage difference of the diode from which current density differs Configuration diagram showing an example of a semiconductor device Configuration diagram showing an example of a power conversion device including a plurality of semiconductor devices Configuration diagram showing an example of a semiconductor device Configuration diagram showing an example of a power conversion device including a plurality of semiconductor devices

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration example of a driving device 1 which is an example of a semiconductor device. The driving device 1 includes a transistor S1, a first diode D1, a path 31, a second diode D2, and a temperature detection circuit 50.

  The transistor S1 is an example of a switching element. The first diode D1 is an example of a first free-wheeling diode connected in antiparallel to the transistor S1. The path 31 is an example of a current path connected in parallel to the first diode D1. The second diode D2 is an example of a second free-wheeling diode inserted in series in the path 31. The temperature detection circuit 50 is an example of temperature detection means for detecting a temperature based on a difference voltage ΔVF between the forward voltage VF1 of the first diode D1 and the forward voltage VF2 of the second diode D2.

  FIG. 2 is a diagram illustrating an example of the temperature dependence of the forward voltage VF of the diode. When current flows through a diode, a forward voltage VF is generated between the anode and cathode of the diode. The forward voltage VF of the diode has a negative temperature characteristic that decreases as the temperature increases. Further, the temperature dependence of the forward voltage VF decreases as the current density of the diode increases. That is, as shown in FIG. 2, the forward voltage VF when the current density is large is less likely to decrease as the temperature increases than when the current density is small.

  Therefore, as shown in FIG. 2, the difference voltage between the forward voltage of the diode having a large current density and the forward voltage of the diode having a small current density gradually increases as the temperature rises. That is, the difference voltage ΔVF between the forward voltage of the diode having a large current density and the forward voltage of the diode having a small current density is a positive temperature characteristic that increases proportionally as the temperature rises as shown in FIG. Have

  Therefore, in the driving device 1 of FIG. 1, the current density of the second diode D2 is set lower than the current density of the first diode D1. Thus, even under a relatively high temperature condition, the temperature detection circuit 50 can accurately determine the temperature based on the difference voltage ΔVF between the forward voltage VF1 of the first diode D1 and the forward voltage VF2 of the second diode D2. Can be detected.

  In addition, since both the first diode D1 and the second diode D2 are freewheeling diodes through which the freewheeling current (forward current) generated during the off period of the transistor S1 flows, a large amount of heat generated by the forward voltage and the forward current. It is the heat source itself that generates loss. Therefore, by using the forward voltage of the heat generation source itself (that is, the forward voltage VF1 of the first diode D1 and the forward voltage VF2 of the second diode D2) for temperature detection, the temperature detection accuracy can be improved by the heat conduction time. It is possible to prevent the deterioration due to the delay of the. Therefore, the temperature detection accuracy can be increased.

  Further, since the first diode D1 and the second diode D2 have both a function of flowing a reflux current and a function of detecting the temperature, the driving device 1 is compared with a case where a diode dedicated to temperature detection is provided separately from the reflux diode. Can be reduced in size and cost.

  Further, the first diode D1 and the second diode D2 are provided on the chip 20 provided with the transistor S1, thereby detecting the temperature of the transistor S1 provided on the same chip as the first diode D1 and the second diode D2 with high accuracy. It becomes possible to do.

  Next, the configuration of FIG. 1 will be described in more detail.

  The driving device 1 includes means for driving an inductive load (for example, an inductor, a motor, or the like) connected to the first conductive unit 61 or the second conductive unit 62 by, for example, driving the transistor S1 on and off. A semiconductor circuit provided.

  The conductive portion 61 is, for example, a current path that is conductively connected to a high power supply potential portion such as a positive electrode of a power supply, and may be indirectly connected to the high power supply potential portion via another switching element or a load. . The conductive portion 62 is a current path that is conductively connected to a low power supply potential portion (for example, a ground potential portion) such as a negative electrode of a power supply, for example, and indirectly connected to the low power supply potential portion via another switching element or a load. May be connected.

  As a device in which one or a plurality of driving devices 1 are used, for example, a power conversion device that converts electric power between input and output by on / off driving of the transistor S1 can be cited. Specific examples of the power converter include a converter that boosts or steps down DC power, an inverter that converts power between DC power and AC power, and the like.

  The transistor S1 is, for example, an IGBT (Insulated Gate Bipolar Transistor) having a gate terminal G, a collector terminal C, and an emitter terminal E. The gate terminal G is a control terminal connected to the gate drive circuit 40, for example. The collector terminal C is, for example, a first main terminal connected to the connection point a and connected to the conductive portion 61 via the connection point a. The emitter terminal E is, for example, a second main terminal connected to the connection point d and connected to the conductive portion 62 via the connection point d.

  The first diode D1 is, for example, a rectifying element having an anode connected to the emitter terminal E and a cathode connected to the collector terminal C. The anode of the first diode D1 is a P-type electrode connected to the connection point d to which the emitter terminal E is connected and connected to the conductive portion 62 through the connection point d. The cathode of the first diode D1 is an N-type electrode connected to the connection point a to which the collector terminal C is connected and connected to the conductive portion 61 through the connection point a.

  For example, the path 31 is connected to the connection point d, connected to the conductive part 62 via the connection point d, connected to the connection point a, and connected to the conductive part 61 via the connection point a. A current path having an end.

  The second diode D2 is, for example, a rectifying element having an anode connected to the voltage detection unit of the temperature detection circuit 50 via the connection point b and a cathode connected to the collector terminal C via the connection point a. .

The drive device 1 includes, for example, a resistor R1 that is inserted in series in the path 31. Thus, in the OFF period of the transistor S1, the current value of the current I ₂ flowing back from the conductive portion 62 to the second diode D2 is smaller than the current I ₁ flowing back from the conductive portion 62 to the first diode D1. Therefore, the current density of the second diode D2 can be made lower than that of the first diode D1. The resistor R1 is connected, for example, between the anode of the second diode D2 and the anode of the first diode D1. Current I ₁ is the current flowing in the forward direction of the first diode D1, current I ₂ is the current flowing in the forward direction of the second diode D2.

For example, the temperature detection circuit 50 monitors the sense voltage Vse generated by the current flowing through the resistor R1 to thereby determine the difference voltage between the forward voltage VF1 of the first diode D1 and the forward voltage VF2 of the second diode D2. ΔVF is detected. Sense voltage Vse is, for example, a voltage generated across the resistor R1 by the current I ₂ flows through the resistor R1.

Assuming that the emitter terminal E (in other words, the connection point d) is a reference potential, the collector voltage Vm of the collector terminal C (in other words, the connection point a) is -VF1 when the first diode D1 and the second diode D2 are energized. Equal (Vm = −VF1). Therefore, when the first diode D1 and the second diode D2 are energized, the sense voltage Vse (in other words, the voltage at the connection point b) is
Vse = Vm + VF2 = VF2-VF1 <0
It becomes.

  Therefore, the temperature detection circuit 50 can detect the difference voltage ΔVF between the forward voltage VF1 and the forward voltage VF2 by monitoring the sense voltage Vse generated in the resistor R1 inserted in series in the path 31. That is, the resistor R1 has a function as a limiting resistor that reduces the current density of the second diode D2 and a function as a detection resistor that detects the differential voltage ΔVF.

The relationship between the forward voltage VF of the diode and the forward current I flowing through the diode can be expressed by Equation 1 by Shockley's diode equation. However, Is is the reverse saturation current, _{V T} represents the thermal voltage.

なお、式１の｛｝の項の中の「−１」は、「Ｅｘｐ（ＶＦ／Ｖ_Ｔ）」に比べて十分小さいため、無視されると、式２が得られる。したがって、式２を変形すると、順方向電圧ＶＦは、式３で表すことができる。

In addition, since “−1” in the {} term of Expression 1 is sufficiently smaller than “Exp (VF / V _T )”, Expression 2 is obtained when ignored. Therefore, when Expression 2 is transformed, the forward voltage VF can be expressed by Expression 3.

  Further, the sense voltage Vse matches “VF2−VF1” as described above. Therefore, the sense voltage Vse can be expressed by Equation 5 using Equation 3 and Equation 4.

ただし、ｋはボルツマン定数、Ｔは絶対温度、ｑは素電荷、Ｉ_１は第１ダイオードＤ１に流れる順方向電流、Ｉ_２は第２ダイオードＤ２に流れる順方向電流、Ｉｓ_１は第１ダイオードＤ１の逆方向飽和電流、Ｉｓ_２は第２ダイオードＤ２の逆方向飽和電流を表す。

Here, k is the Boltzmann constant, T is the absolute temperature, q is the elementary charge, _{I 1} is the forward current flowing through the first diode D1, _{I 2} is the forward current flowing through the second diode D2, Is ₁ the first diode D1 reverse saturation current of, is ₂ represents a reverse saturation current of the second diode D2.

The reverse saturation current Is is proportional to the junction area of the diode. Therefore, (Is ₁ / Is ₂ ) represents the junction area ratio of the first diode D1 and the second diode D2, that is, the size ratio S. Therefore, when Equation 5 is transformed, the absolute temperature T can be expressed by Equation 6.

なお、ｎ（＝Ｉ_１／Ｉ_２）は、第１ダイオードＤ１に流れる電流Ｉ_１と第２ダイオードＤ２に流れる電流Ｉ_２の電流値の比（＝センス比）を表す（ただし、ｎ＞Ｓ）。

Note that n (= I ₁ / I ₂ ) represents the ratio (= sense ratio) of the current value of the current I ₁ flowing through the first diode D ₁ and the current I ₂ flowing through the second diode D 2 (where n> S ).

  Therefore, since q and k are known values and n and S are also known design values, the temperature detection circuit 50 can estimate the absolute temperature T according to Equation 6 by detecting the sense voltage Vse.

  The temperature detection circuit 50 outputs temperature information, for example, according to the detected sense voltage Vse. Examples of the temperature information include a detected value of the difference voltage ΔVF (that is, the sense voltage Vse), an estimated value of the absolute temperature T, and the like.

  The drive device 1 includes a gate drive circuit 40, for example. The gate drive circuit 40 turns on and off the transistor S1 according to the drive signal. The drive signal is a command signal for instructing on / off of the transistor S1, and is a signal (for example, a pulse width modulation signal) supplied from an external device such as a microcomputer higher than the drive device 1.

  FIG. 4 is a diagram illustrating a configuration example of the driving device 2 which is an example of the semiconductor device. A description of the same configurations and effects as those of the above-described embodiment will be omitted. The resistor R1 inserted in series in the path 31 may be connected between the cathode of the second diode D1 and the cathode of the first diode D1.

Assuming that the emitter terminal E (in other words, the connection point d) is a reference potential, when the first diode D1 and the second diode D2 are energized, the sense voltage Vse is as shown in FIG.
Vse = −VF2 − (− VF1) = VF1−VF2> 0
It becomes.

  Therefore, the temperature detection circuit 50 can detect the difference voltage ΔVF between the forward voltage VF1 and the forward voltage VF2 by monitoring the sense voltage Vse generated in the resistor R1 inserted in series in the path 31. That is, the resistor R1 has a function as a limiting resistor that reduces the current density of the second diode D2 and a function as a detection resistor that detects the differential voltage ΔVF.

  FIG. 5 is a configuration diagram illustrating an example of a power conversion device 101 including a plurality of drive devices. A description of the same configurations and effects as those of the above-described embodiment will be omitted.

  The power conversion device 101 includes two drive devices 3L and 3H, and an arm circuit in which transistors provided on the high side and the low side are connected in series to an intermediate node 65 to which an inductive load 70 is connected. 66. When used as an inverter that drives a three-phase motor, the power conversion device 101 includes three arm circuits 66 in parallel with the same number of phases as the three-phase motor.

  The conductive portion 61H connected to the high-side transistor S12 is conductively connected to the high power supply potential portion 63, and the conductive portion 62H connected to the transistor S12 is connected to the low power supply potential via the low-side transistor S11 or the load 70. It is indirectly connected to the unit 64. On the other hand, the conductive portion 62L connected to the low-side transistor S11 is conductively connected to the low power supply potential portion 64, and the conductive portion 61L connected to the transistor S11 is connected to the high power supply potential portion via the transistor S12 or the load 70. 63 is indirectly connected.

  The driving devices 3L and 3H are examples of semiconductor devices, and have the same circuit configuration. Therefore, the following detailed description about the drive device 3L is incorporated in the drive device 3H.

  The driving device 3L includes a transistor S11 that is an example of a switching element. The transistor S11 is an insulated gate voltage control semiconductor element with a current sensing function, and has a gate terminal G, a collector terminal C, an emitter terminal E, and a sense emitter terminal SE.

  The gate terminal G is a control terminal connected to the gate drive circuit 40 of the control circuit 91L, for example. The collector terminal C is, for example, a first main terminal connected to the connection point a and connected to the conductive portion 61L via the connection point a. The emitter terminal E is, for example, a second main terminal connected to the connection point d and connected to the conductive portion 62L via the connection point d. The sense emitter terminal SE is, for example, a sense terminal connected to the connection point b and connected to the temperature detection circuit 50 and the abnormality detection circuit 80 via the connection point b.

  The transistor S11 includes a main transistor 12 and a sense transistor 13. The main transistor 12 and the sense transistor 13 are switching elements such as IGBTs. The sense transistor 13 is connected in parallel to the main transistor 12. Each of the main transistor 12 and the sense transistor 13 may be composed of a plurality of cell transistors.

  The gate electrodes of the main transistor 12 and the sense transistor 13 are control electrodes commonly connected to the gate terminal G of the transistor S11. The collector electrodes of the main transistor 12 and the sense transistor 13 are first main electrodes commonly connected to the collector terminal C of the transistor S11. The emitter electrode of the main transistor 12 is a second main electrode connected to the emitter terminal E of the transistor S11. The sense emitter electrode of the sense transistor 13 is a sense electrode connected to the sense emitter terminal SE of the transistor S11.

  The main transistor 12 is an example of a switching element. The sense transistor 13 is an example of a sense switching element that generates a current corresponding to the current flowing through the main transistor 12. The sense transistor 13 is a sense element through which a larger current flows as the current flowing through the main transistor 12 increases. For example, the sense transistor 13 outputs a sense current Ise proportional to the main current Ie flowing through the main transistor 12.

  For example, the collector current flowing into the transistor S11 from the collector terminal C is divided into the main current Ie flowing through the main transistor 12 and the sense current Ise flowing through the sense transistor 13 with a sense ratio m. The sense current Ise is a current that flows at a ratio of the sense ratio m according to the main current Ie, and is a current whose current value is smaller than the main current Ie by the sense ratio m. The sense ratio m is determined according to, for example, a ratio between the area of the emitter electrode of the main transistor 12 and the area of the sense emitter electrode of the sense transistor 13.

The main current Ie flows through the collector electrode and the emitter electrode in the main transistor 12 and is output from the emitter terminal E. The main current Ie output from the emitter terminal E flows through the conductive portion 62L via the connection point d. The main current Ie, the forward direction of the diode current I ₁ flowing through the main diode D11 is a reverse current.

The sense current Ise flows through the collector electrode and the sense emitter electrode in the sense transistor 13 and is output from the sense emitter terminal SE. The sense current Ise output from the sense emitter terminal SE flows through the conductive portion 62L via the resistor R1 and the connection point d. Sense current Ise, the sense diode current I ₂ in the forward direction flows through the sensing diode D12 is a reverse current.

  The driving device 3L includes a main diode D11 and a sense diode D12. The main diode D11 is an example of a first free-wheeling diode connected to the main transistor 12 in antiparallel.

The sense diode D12 is an example of a second freewheeling diode inserted in series in a path 31 connected in parallel to the main diode D11. The sense diode D12 is an example of a sense diode that generates a sense current corresponding to a current flowing through the main diode D11. The sense diode D12 is a sense element through which a larger current flows as the current flowing through the main diode D11 increases. Sensing diode D12, for example, and outputs a sense diode current _{I 2} proportional to the diode current _{I 1} flowing through the main diode D11.

Sense diode current I ₂ is the current flowing at the rate of sense ratio n according to the diode current I _1, the current value than the diode current I ₁ is small currents by the sense ratio n. Sense diode current I ₂ is the current flowing in the forward direction of the sensing diode D12.

  The anode of the sense diode D12 is a P-type electrode connected to the connection point b to which the sense emitter terminal SE is connected and connected to the voltage detection unit of the temperature detection circuit 50 through the connection point b. The cathode of the sense diode D12 is an N-type electrode connected to the connection point a to which the collector terminal C is connected and connected to the conductive portion 61 through the connection point a.

Temperature detection circuit 50, for example, by monitoring the negative sense voltage Vse generated by flowing a sense diode current _{I 2} to the resistor R1, the forward voltage VF2 of the forward voltage VF1 and the sense diode D12 of the main diode D11 The difference voltage ΔVF is detected. In this case, the sense voltage Vse is, for example, a voltage generated across the resistor R1 by the sense diode current I ₂ flows through the resistor R1.

During energization of the main diodes D11 and sensing diode D12, the temperature detection circuit 50, for example, by detecting the voltage difference ΔVF by monitoring the negative sense voltage Vse a sense diode current I ₂ is generated by flowing through the resistor R1 Thus, the absolute temperature T can be estimated.

  The drive device 3L includes an abnormality detection circuit 80. The abnormality detection circuit 80 is an example of an abnormality detection unit that detects an abnormality of the main current Ie flowing through the main transistor 12 based on the positive sense voltage Vse generated when the sense current Ise passes through the resistor R1. In this case, the sense voltage Vse is, for example, a voltage generated at both ends of the resistor R1 when the sense current Ise flows through the resistor R1.

  When the transistor S11 is energized, the abnormality detection circuit 80 compares the positive sense voltage Vse generated when the sense current Ise flows through the resistor R1 with a predetermined reference voltage, for example, so that the main current Ie becomes an abnormal current ( For example, it can be determined whether it is an overcurrent or a short-circuit current. For example, the abnormality detection circuit 80 determines that the main current Ie is an overcurrent when it is detected that the positive sense voltage Vse exceeds a predetermined reference voltage.

  The abnormality detection circuit 80 outputs an abnormal current detection signal according to the detected sense voltage Vse. Examples of the abnormal current detection signal include a detection value of the differential voltage ΔVF (that is, the sense voltage Vse), an abnormal current determination signal, and the like.

  When the abnormality of the main current Ie is detected by the abnormality detection circuit 80, for example, the transistor S11 is turned off by the gate drive circuit 40. Since the main transistor 12 and the sense transistor 13 are turned off by turning off the transistor S11, an abnormal flow of the main current Ie can be cut off.

  Thus, since the sense emitter terminal SE has both a function for temperature detection and a function for current abnormality detection, the temperature detection terminal and the current abnormality detection terminal can be shared. Further, by sharing the terminals, it is possible to share the wiring connected to the terminals.

The temperature detection circuit 50 of the control circuit 91L, when the diode current I ₁ flowing back from the low side of the main diode D11 to the load 70 through the intermediate node 65 flows, for example, can detect the temperature of the low-side transistor S11. On the other hand, the abnormality detection circuit 80 of the control circuit 91L detects the abnormality of the main current Ie flowing into the low-side main transistor 12 when the main current Ie flowing into the low-side main transistor 12 flows from the load 70 through the intermediate node 65. It can be detected. The main diode D11 and the sense diode D12 are provided on the chip 21 where the low-side main transistor 12 and the sense transistor 13 are provided, so that the effect of detecting the temperature of the low-side transistor S11 with high accuracy can be enhanced.

On the other hand, the temperature detection circuit 50 of the control circuit 91H, when the diode current I ₁ flows back to the main diode D21 of the high-side from the load 70 via the intermediate node 65 flows, for example, can detect the temperature of the transistor S12 in the high side . On the other hand, the abnormality detection circuit 80 of the control circuit 91H detects the main current Ie flowing from the high-side main transistor 12 when the main current Ie flowing from the high-side main transistor 12 to the load 70 through the intermediate node 65 flows. Anomalies can be detected. The main diode D21 and the sense diode D22 are provided on the chip 22 where the high-side main transistor 12 and the sense transistor 13 are provided, so that the effect of detecting the temperature of the high-side transistor S12 with high accuracy can be enhanced. Become.

  FIG. 6 is a configuration diagram illustrating an example of a driving device 4 that is an example of a semiconductor device. A description of the same configuration as that of the above-described embodiment is omitted. The drive device 4 may be applied to the power conversion device shown in FIG.

  As the sense current Ise flows through the resistor R1, a sense voltage Vse corresponding to the magnitude of the main current Ie is generated across the resistor R1. For example, the abnormality detection circuit 80 can detect the magnitude of the main current Ie by detecting a positive voltage value of the sense voltage Vse.

  The abnormality detection circuit 80 may include a comparator 81, for example. The comparator 81 compares the sense voltage Vse and the positive reference voltage Vref1, and outputs an abnormal current detection signal corresponding to the comparison result. When it is detected that the sense voltage Vse is higher than the positive reference voltage Vref1, the comparator 81 determines that an overcurrent (or a short-circuit current) is flowing through the transistor S1, and outputs a high-level abnormal current detection signal. Output.

  When a high-level abnormal current detection signal is output from the abnormality detection circuit 80, for example, the transistor S1 is turned off by the gate drive circuit 40. Since the main transistor 12 and the sense transistor 13 are turned off by turning off the transistor S1, an abnormal flow of the main current Ie can be cut off.

On the other hand, by a sense diode current I ₂ flows through the resistor R1, the sense voltage Vse in accordance with the magnitude of the diode current I ₁ is generated across the resistor R1. For example, the temperature detection circuit 50 can detect the temperature of the first diode D1 and the second diode D2 or the temperature of the main transistor 12 and the sense transistor 13 by detecting a negative voltage value of the sense voltage Vse. Further, for example, the temperature detection circuit 50 can detect the magnitude of the diode current I ₁ by detecting a negative voltage value of the sense voltage Vse.

  The temperature detection circuit 50 may include a comparator 51, for example. The comparator 51 compares the sense voltage Vse with the negative reference voltage Vref2, and outputs an overheat detection signal corresponding to the comparison result. When it is detected that the sense voltage Vse is lower than the negative reference voltage Vref2, the comparator 51 determines that the first diode D1 or the main transistor 12 is abnormally overheated, and outputs a low level overheat detection signal.

  When a low-level overheat detection signal is output from the temperature detection circuit 50, for example, the transistor S1 is turned off by the gate drive circuit 40. Since the main transistor 12 and the sense transistor 13 are turned off by turning off the transistor S1, an abnormal temperature rise of the first diode D1 or the main transistor 12 can be prevented.

  Therefore, the resistor R1 and the sense emitter terminal SE can have both the function of detecting the abnormality of the main current Ie and the function of detecting the temperature, so that the size and the cost can be reduced.

  FIG. 7 is a configuration diagram illustrating an example of a power conversion device 102 including a plurality of drive devices. A description of the same configurations and effects as those of the above-described embodiment will be omitted.

  The driving devices 5L and 5H are examples of semiconductor devices, and have the same circuit configuration. Therefore, the following detailed description about the drive device 5L is incorporated in the drive device 5H.

  The transistor S11 is, for example, a diode built-in IGBT in which the main transistor 12, the sense transistor 13, the main diode D11, and the sense diode D12 are provided in a common chip 21. The diode built-in IGBT has a structure in which the anode electrode of the diode and the emitter electrode of the IGBT are used as a common electrode, and the cathode electrode of the diode and the collector electrode of the IGBT are used as a common electrode. The diode built-in IGBT is also referred to as reverse conducting IGBT (Reverse Conducting (RC) -IGBT). The sense emitter terminal SE is, for example, a sense terminal connected to the connection point b and connected to the temperature detection circuit 50 and the energization direction determination circuit 85 via the connection point b.

Current direction judgment circuit 85, based on the sense voltage Vse generated by sense diode current I ₂ flows back to the sensing diode D12 is through a resistor R1, an example of the off-control means for maintaining the OFF state of the main transistor 12 is there. The energization direction determination circuit 85 can determine that the transistor S11 is energized when the positive sense voltage Vse is detected, and can determine that the main diode D11 is energized when the negative sense voltage Vse is detected.

When the determination signal notifying that the main diode D11 is determined to be energized is input to the gate drive circuit 40, the gate drive circuit 40 maintains the transistor S11 in the off state even if the drive signal for turning on the transistor S11 is supplied. Thus, when the diode current I ₁ is flowing, it is possible to prevent the main transistor 12 and the sense transistor 13 is turned on. Further, when the diode current I ₁ is flowing, the main transistor 12 and the sense transistor 13 by turning on, it is possible to prevent the loss of main diodes D11 and sensing diode D12 is increased.

Temperature detection circuit 50, for example, by monitoring the negative sense voltage Vse generated by flowing a sense diode current _{I 2} to the resistor R1, the forward voltage VF2 of the forward voltage VF1 and the sense diode D12 of the main diode D11 The difference voltage ΔVF is detected. During energization of the main diodes D11 and sensing diode D12, the temperature detection circuit 50, for example, by detecting the voltage difference ΔVF by monitoring the negative sense voltage Vse a sense diode current I ₂ is generated by flowing through the resistor R1 Thus, the absolute temperature T can be estimated.

  The energization direction determination circuit 85 functions as an abnormality detection unit that detects an abnormality of the main current Ie flowing through the main transistor 12 based on the positive sense voltage Vse generated when the sense current Ise passes through the resistor R1 (for example, The function of the abnormality detection circuit 80 described above may also be provided.

  Although the semiconductor device has been described above by way of the embodiment, the present invention is not limited to the above embodiment. Various modifications and improvements such as combinations and substitutions with some or all of the other embodiments are possible within the scope of the present invention.

  For example, the semiconductor device may be a semiconductor device having a configuration formed by an integrated circuit, or may be a semiconductor device having a configuration formed by discrete components.

  The transistor may be a switching element other than the IGBT, and may be, for example, an N-channel or P-channel MOSFET (Metal Oxide Semiconductor Field Effect Transistor), or an NPN-type or PNP-type bipolar transistor. In the case of a MOSFET, it may be read by replacing “collector” with “drain” and “emitter” with “source”, and in the case of bipolar transistor, it may be read by replacing “gate” with “base”.

  Moreover, although the above-mentioned embodiment shows the case where the current density of the 2nd freewheeling diode is lower than the current density of the 1st freewheeling diode, the current density of the 1st freewheeling diode is 2nd freewheeling diode. Even when the current density is lower than that, the temperature can be detected with high accuracy.

  For example, in FIG. 1, the resistance R1 is changed from a series connection with the second diode D2 to a series connection with the first diode D1, thereby making the current density of the first diode D1 higher than the current density of the second diode D2. Can be lowered. Similarly, in FIG. 5, for example, if a necessary condition such as the absence of the abnormal current detection circuit 80 is satisfied, the resistor R1 is changed from a series connection with the sense diode D12 to a series connection with the main diode D11. The current density of the main diode D11 can be made lower than the current density of the sense diode D12.

1, 2, 3L, 3H, 4, 5L, 5H Drive device (example of semiconductor device)
DESCRIPTION OF SYMBOLS 12 Main transistor 13 Sense transistor 20, 21, 22 Chip 31 Current path 40 Gate drive circuit 50 Temperature detection circuit 61, 62 Conductive part 70 Load 80 Abnormality detection circuit 85 Energization direction determination circuit 91L, 91H Control circuit 101, 102 Power conversion device D1 First diode D2 Second diode D11 Main diode D12 Sense diode R1 Resistance S1, S11, S12 Transistor

Claims (7)

A switching element;
A first freewheeling diode connected in antiparallel to the switching element;
A current path connected in parallel to the first freewheeling diode;
A second freewheeling diode inserted in series with the current path;
Temperature detecting means for detecting a temperature based on a difference voltage between a forward voltage of the first freewheeling diode and a forward voltage of the second freewheeling diode;
A semiconductor device in which a current density of the first free-wheeling diode and a current density of the second free-wheeling diode are different from each other.   The semiconductor device according to claim 1, wherein a current density of the second freewheeling diode is lower than a current density of the first freewheeling diode.   3. The semiconductor device according to claim 2, wherein the temperature detection unit detects the differential voltage by monitoring a voltage generated when a current flows through a resistor inserted in series in the current path.   The semiconductor device according to claim 3, wherein the resistor is connected between an anode of the second free-wheeling diode and an anode of the first free-wheeling diode. A sense switching element that generates a sense current according to a current flowing through the switching element;
The semiconductor device according to claim 4, further comprising: an abnormality detection unit that detects an abnormality of the current flowing through the switching element based on a sense voltage generated when the sense current passes through the resistor.   6. The semiconductor according to claim 4, further comprising an off control unit configured to maintain an off state of the switching element based on a sense voltage generated when a return current flowing through the second return diode passes through the resistor. apparatus.   The semiconductor device according to claim 1, wherein the first free-wheeling diode and the second free-wheeling diode are provided on a chip on which the switching element is provided.

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